package leetcode.primary;

public class T63 {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int m = obstacleGrid.length;
        int n = obstacleGrid[0].length;

        if (obstacleGrid[0][0]==1){
             return 0;
        }
        int[][] dp = new int[m][n];


        for (int i=0;i<m;i++){
            if (obstacleGrid[i][0]==0){
                dp[i][0] = 1;
            }else {         //如果第一列有障碍物，则后面的路径数全为0
                break;
            }
        }
        for (int j = 0; j < n; j++) {
            if (obstacleGrid[0][j]==0){
                dp[0][j] = 1;
            }else {
                break;
            }
        }

        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j]==1){
                    dp[i][j] =0;
                }else {
                    dp[i][j] = dp[i-1][j]+dp[i][j-1];
                }
            }
        }

        return dp[m-1][n-1];
    }

    public static void main(String[] args) {
        T63 test = new T63();
        int paths = test.uniquePathsWithObstacles(new int[][]{{0,0,0}});
        System.out.println("paths="+paths);
    }
}
